Neurosurg Focus 10 (6):Article 4, 2001, Click here to return to Table of Contents

Pediatric supratentorial intraventricular tumors

DANIEL Y. SUH, M.D., PH.D., AND TIMOTHY MAPSTONE, M.D. Department of Neurosurgery, Emory University School of Medicine, and the Children’s Healthcare of Atlanta-Egleston, Atlanta, Georgia

A variety of mass lesions can arise within or in proximity to the ventricular system in children. These lesions are relatively uncommon, and they present a unique diagnostic and surgical challenge. The differential diagnosis is deter- mined by tumor location in the ventricular system, clinical presentation, age of the patient, and the imaging character- istics of the lesion. In this report the authors provide an introduction to and an overview of the most common pediatric supratentorial intraventricular tumors. The typical radiographic features of each tumor and location preference within the ventricular system are reviewed. Management and treatment considerations are discussed. Examination of tissue samples to obtain diagnosis is usually required for accurate treatment planning, and resection without adjuvant thera- pies is often curative. The critical management decision frequently involves determining which lesions are appropri- ate for surgical therapy. Care ful preoperative neuroimaging is extremely useful in planning surgery. Knowledge of the typical imaging characteristics of these tumors can help to determine the diagnosis with relative certainty when a tis- sue sample has not been obtained, because a small subset of these lesions can be managed expectantly.

KEY WORDS ¥ intraventricular tumor ¥ pediatric tumor ¥ brain lesion ¥ hydrocephalus

One tenth of all CNS neoplasms present within or in certain anatomical locations and in certain age groups.61,75, proximity to the ventricular system.85 These neoplasms 80,85,92,124,133 Table 1 provides a list of common pediatric comprise a heterogeneous group with regard to tumor type intraventricular tumors by ventricular location. The imag- and clinical prognosis in both children and adults. Al- ing characteristics of these lesions are also described in though some of these tumors are aggressive high-grade Table 2.75,85,124 Although these distinctions may seem arbi- lesions, many are histologically benign and potentially trary as most of these tumors occur in patients throughout curable by undertaking resection. Because they tend to the ventricular system and across a wide range of ages, grow slowly, however, they may remain clinically silent tumor location, age of the patient, and imaging character- and reach significant size before becoming symptomatic, istics are helpful in determining the differential diagnosis. making the excision technically challenging. Typically, To make the distinction between intra- and extraventricu- these lesions cause symptoms and signs of increased ICP lar lesions also aids in differential diagnosis and guides in due to hydrocephalus, which will vary depending on the planning the surgical approach. age of the patient. An older child with raised ICP will Microsurgical resection has been the treatment of complain of persistent headache or have episodes of vom- choice for the majority of these lesions. The use of stereo- iting that characteristically occur in the morning. In the tactic navigational systems to assist in volumetric resec- nonverbal child or infant, the only evidence of increased tion of intraventricular tumors has also been described.79 ICP may be nonspecific signs of irritability, loss of ap- Minimally invasive neuroendoscopic techniques used to petite, anhedonia, or a finding of macrocrania. Specific diagnose and potentially resect intraventricular tumors focal neurological deficits occur depending on tumor lo- may ultimately prove to be as effective as microsurgical cation and involvement of adjacent structures or sur- approaches.38 The propensity of intraventricular tumors to rounding cerebral parenchyma. reach significant size at presentation as well as the risk of Specific tumor types appear to occur more frequently in significant bleeding with piecemeal resection, especially in cases of lateral ventricular tumors limit the role of en- doscopic techniques to selected cases. Tumor histological Abbreviations used in this paper: CNS = central nervous system; type and location as well as the presence and degree of CPP = choroid plexus papilloma; CPC = choroid plexus carci- neurological deficit determine the management in the noma; CSF = cerebrospinal fluid; CT = computerized tomography; GCT = germ cell tumor; HCG = human chorionic gonado- individual patient. tropinÐ; JPA = juvenile pilocytic astrocytoma; ICP = intracranial pressure; MR = magnetic resonance; NF = neurofibromatosis; TUMORS OF THE LATERAL VENTRICLES PNET = primitive neuroectodermal tumor; SGCA = subependymal giant cell astrocytoma. Fewer than 1% of all intracranial neoplasms arise with-

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TABLE 1 Pediatric supratentorial intraventricular neoplasms by location*

Location Tumor

lat ventricles trigone CPP, ependymoma, meningioma (rare) body astrocytoma, PNET, teratoma FH/SP SGCA, PA, PNET third ventricle FOM/ant 3rd ventricle PA, craniopharyngioma, germinoma, CPP (rare), colloid cyst (rare) FOM/pos 3rd ventricle pineal, high-grade astrocytoma, ependymoma, germ cell * ant = anterior; FH/SP = frontal horn/septum pellucidum; FOM = foramen of Monro; PA = pilocytic astrocytoma; pos = posterior; SGCA = subependymal giant cell tumor. in the lateral ventricles, although the incidence of lateral reported the incidence of tumors within the lateral ventri- ventricular tumors may be higher in the pediatric popula- cle in descending order of frequency: trigone (50%), body tion.133 One half of all adult intraventricular tumors and (35%), frontal horn (10%), and temporal horn (5%). In one quarter of pediatric tumors occur in the lateral ventri- contrast to the results of Piepmeier,92 metaanalysis of the cle.91 Histological diagnosis varies with both the age of data further suggests that the incidence of tumors occur- the patient61,75,80,85,124 and the specific location of the le- ring in the body of lateral ventricle (27.6%) may actually be sion within the ventricle itself.75,80,92 Data reported in three similar to that of tumors found in the frontal horn (26.6%). large series of patients harboring intraventricular mass- In children, intraventricular neoplasms occur more of- es61,75,80 were combined for further analysis. Despite the ten in the trigone, primarily because certain tumor types obvious limitations in these studies, including lack of that favor the trigonal region have a predilection for oc- complete histological data,75 lack of inclusion of certain curing in children. Zuccaro, et al.,133 have examined a se- tumor types, the grouping of children and adults, inherent ries of 54 children and young adults, ranging in age from selection biases, and lack of uniformity in determining 15 days to 20 years, with histologically proven lateral ven- lesion location, certain obvious trends are apparent. In all tricular tumors surgically treated over a 10-year period. three studies, the trigone is the most common site for tu- The trigone and frontal horn were the most common sites mors arising in the lateral ventricles, with rates ranging of origin (15 [27.8%]) of 54 patients, followed in order of from 38 to 56%. This finding is consistent with data re- frequency by posterior horn (six [11%]), temporal horn ported by Piepmeier.92 In a series of 22 patients, the author (five [9.3%]), and panventricular or frontotemporooccipi-

TABLE 2 Imaging characteristics of common pediatric supratentorial intraventricular tumors*

CT Characteristics MR Imaging Characteristics†

Neoplasm Density Calcified Enhancement T1 intensity T2 intensity Enhancement Comment CPP isoÐhyper 25% +++ hypo isoÐhyper + trigone in children; all ven- (3/4) tricles dilated; may be locally invasive CPC iso 25% +++ hypo isoÐhyper + trigone in children; craniospi- nal dissemination astrocytoma iso 15Ð20% + hypo hyper + pilocytic: cystic, mural nodule (low-grade) may enhance intensely SGCA mixed (isoÐ common +++ hypoÐiso isoÐhyper ++ tuberous sclerosis; arise in re- hypo) gion of FOM ependymoma iso (50%) ++ hypo hyper ++ supratentorial ependymomas arise in trigone, cystic; local recurrence meningioma hyper (20Ð25%) +++ iso iso +++ rare in children; cystic; can be multiple; NF-2 PNET hyper common + hypo hyper + to ++ neonates and infants; highly malignant central neurocytoma isoÐhyper yes ++ iso isoÐhyper + to ++ immunohistochemistry germinoma hyper uncommon +++ isoÐhyper isoÐhypo + CSF & serum tumor markers teratoma mixed yes mixed mixed heterogeneous & variable imaging characteristics craniopharyngioma hyper yes (90% rim +++ hypo hyper +++ cystic: adamantinomatous; calcified) children adults; solid: papillary; adults children colloid cyst iso (1/3) no rim hyper hypo rim mixed MR signal based on hyper (2/3) cyst content * + = minimal; ++ = moderate; +++ = marked; Ð = none. † Refers to T1- and T2-weighted images.

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC Pediatric supratentorial intraventricular tumors tal (four [7.4%]). Seventeen percent were bifrontal tu- benign cellular appearance.65 This variant of CPP has in mors. The most frequent tumor types were SGCA (14 the past been diagnosed as a CPC, although these tumors [25.9]%); choroid plexus tumors (12 [22.2%]: nine papil- appear to be distinct from CPCs in that gross-total resec- lomas [16.7%] and three carcinomas [3.7%]); ependymo- tion without adjuvant therapy may be curative. mas (eight [14.8%]); and astrocytomas (six [11.1%]). Patients with CPPs usually present with signs of hydro- cephalus and marked ventricular dilation. In 80% of cases, Trigonal Lesions ventricular enlargement occurs without obvious evidence Choroid plexus tumors are one of the most common le- of obstruction, implicating CSF overproduction or malab- sions of the lateral ventricle in young children, and the sorption in the pathogenesis. These lesions are iso- to hy- 12,61,75,80,133 majority occurs within the trigone. Ependymo- perdense on CT scans, hypointense on T1-weighted MR mas and low-grade astrocytomas (for example, pilocytic images, and iso- to hyperintense on T2-weighted MR im- astrocytomas and SGCAs) occur in the trigonal region in ages (Fig. 1). Tumor margins are irregular, mottled mass- older children and young adults. Intraventricular menin- es, reflecting a frondlike surface. Because CPPs are high- giomas typically occur in the trigonal region in older ly vascular lesions, they strongly enhance with contrast adults, although they can arise in children. Two nonneo- administration. Enlarged choroidal arteries are often pre- plastic lesions that frequently present as trigonal lesions sent, and the lateral posterior choroidal arteries frequently are choroid plexus cysts and xanthogranulomas, both of represent the major blood supply. Tumor calcification which are benign, typically asymptomatic lesions that occurs in 25% of lesions but is relatively uncommon in occur bilaterally and are found incidentally. The former lesions found in children. are epithelial-lined cysts located in the glomus that can be Complete resection of well-differentiated papillomas is seen in neonates. The latter are choroid plexus masses that essentially curative, and adjuvant therapies are not need- typically occur in adults but are occasionally found in ed.26,30,76,77,90,116 The critical aspect of the surgical approach children. is to expose the vascular pedicle during the initial stage of Choroid Plexus Papilloma and Carcinoma. Choroid the procedure to avoid avulsion of the feeding arteries, plexus papillomas account for approximately 2 to 5% of which can occur when manipulating these large lesions. all intracranial neoplasms in children and 10 to 20% of Moreover, attempts to debulk the tumor without control of tumors that occur in the first year of life.30,44 Choroid the vascular pedicle can result in significant blood loss plexus papillomas are the most common lateral ventricu- and subsequent morbidity and or mortality.26,90,116 For lar tumor in children, with the vast majority (70Ð90%) of these reasons, microsurgical rather than endoscopic ap- these tumors occurring in children younger than 2 years of proaches are favored, although small CPPs have been suc- age.12,65,90 In older children and adolescents, these lesions cessfully resected using endoscopic techniques.38 Preop- demonstrate a propensity for the fourth ventricle, mirror- erative angiographic evaluation and embolization can be ing the same anatomical preference as that seen in adults. extremely useful in cases of highly vascular lesions. Mul- There appears to be a slight male preponderance. Choroid tistaged procedures or the use of specialized equipment plexus papillomas are histologically benign lesions that such as the argon-beam coagulator have also been pro- may show focal brain invasion.17 In one report the authors posed by some authors119 as necessary in cases of extreme- have described a subset of atypical CPPs that demonstrate ly hypervascular tumors; others have argued that multiple local parenchymal invasion and loss of the normal villus subtotal resection procedures only increase the risk of sig- architecture at the site of invasion but otherwise have a nificant perioperative bleeding.74 Complete resection may

Fig. 1. Imaging studies of CPP. Axial noncontrast CT scan (A) revealing a large right lateral intraventricular mass in

the trigonal region with associated hydrocephalus. Axial T1- (B) and T2-weighted (C) MR images without gadolinum, demonstrating a large intraventricular mass extending from the atrium of the right lateral ventricle to the temporal horn.

The mass has lobulated margins and is slightly heterogeneous in signal on both T1- and T2-weighted sequences with a few small areas of necrosis or cystic change. There are areas of low signal intensity, which likely represent hemorrhage and are best seen on the hemosiderin sequences (not shown). Contrast-enhanced images (not shown) demonstrate a fair- ly homogeneous enhancement pattern. No remote CSF seeding was seen.

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC D. Y. Suh and T. Mapstone not eliminate the need for CSF diversion. Resection range from 26 to 50%. Because of their invasive nature should be followed by a trial of ventricular drainage, be- and propensity to metastasize, however, most CPCs are cause hydrocephalus may persist even after successful not amenable to gross-total resection. Moreover, whereas excision necessitating placement of a shunt in up to 50% gross-total resection of CPC is associated with the most of patients.26,90 In patients with residual tumor, second- favorable outcome, it remains unclear whether improved look surgery has been recommended by some investi- outcome is attributable to resection alone or reflects more gators to achieve complete resection.26 Finally, a key tech- favorable tumor biology nature (that is, degree of invasion nical detail following any transcortical resection of an and/or extent of vascularity).42Although some encourag- intraventricular and/or paraventricular tumor is the clo- ing results have been reported for postoperative radiother- sure of the corticotomy by using biological glue or fibrin apy30,133 and chemotherapy in patients with CPC,28,42,115 the adhesive to minimize the risk of postoperative subdural contribution of adjuvant therapies over and above gross- fluid collections.3,52,90 Such postoperative collections have total resection remains unclear. Postoperative chemo- been associated with poor outcome following the resec- therapy has not been shown to prevent recurrence in these tion of CPPs.90 tumors, although postoperative radiotherapy may be ef- Choroid plexus carcinomas are uncommon lesions, ac- fective against recurrence in older children.90 In cases in counting for approximately one third of choroid plexus which complete resection is not possible, however, adju- neoplasms.116Almost all of these lesions occur in infants vant chemotherapy following acquisition of a biopsy sam- and children (2Ð4 years of age) and arise in the lateral ven- ple has been used with some success as a preoperative reg- tricles. Distinguishing between CPP and CPC can some- imen to help improve the chance of gross-total resection at times be difficult based on pathological criteria, although reoperation.116 Whether this combination of preoperative immunohistochemistry can help to differentiate between chemotherapy followed by resection offers survival bene- the two. Choroid plexus carcinomas express keratin as a fits comparable with radical resection performed as an ini- function of their epithelial differentiation but seldom ex- tial intervention is not clear. press S-100 protein, glial fibrillary acid protein, or trans- Ependymoma. Approximately 8 to 13% of all child- thyretin, all of which are frequently expressed by CPPs. hood intracranial neoplasms are ependymomas;49 two These lesions demonstrate intraparenchymal infiltration thirds arise in the posterior fossa, and one third are supra- with cellular atypia and conspicuous mitoses. In contrast tentorial. Supratentorial ependymomas are largely intra- to the rarity of craniospinal dissemination in CPPs,32 cran- or paraventricular masses most commonly associated with iospinal dissemination is common in CPCs, and, on occa- the lateral ventricles, but they may also present as isolated sion, these lesions may undergo systemic metastasis. Im- third ventricular masses.88 Most of them arise in the trigo- aging characteristics can be helpful in distinguishing CPC nal region or body of the lateral ventricle.61,75,133 On CT from CPP. Choroid plexus carcinomas demonstrate het- scans, ependymomas appear to be solid masses, isodense erogeneous enhancement, intraparenchymal invasion, pe- to hyperdense to brain, with variable enhancement after ritumoral parenchymal edema, and evidence of dissemi- contrast administration. Supratentorial ependymomas are nation through the subarachnoid space (Fig. 2). often associated with a cyst, although the cystic nature of Total excision is the major predictor of long-term sur- these lesions does not appear to confer benign histology.20 vival in patients with CPC;9,29,30,42 the 5-year survival rates Magnetic resonance studies demonstrate heterogeneous

Fig. 2. Magnetic resonance imaging studies of CPC. Axial T1- (A) and T2-weighted (B) precontrast MR images demonstrating a lobulated mixed signal intensity mass that appears to arise in the atrium of the right lateral ventricle. The choroid plexus appears to be the site of origin. The tumor extends into the parietal lobe white matter. There is also exten- sion peripherally into the subcortical region. Extensive vasogenic edema in the right parietal, occipital, and posterior tem- poral lobes is noted. Edema also extends into the external capsule on the right. There is mass effect with distortion of the right thalamus and brainstem with effacement of the right perimesencephalic cistern. No hydrocephalus is seen. Axial hemosiderin-sequence MR image (C) demonstrating an area of low signal intensity, suggesting the presence of blood

products. Axial T1-weighted MR scan with gadolinum (D) revealing marked enhancement. A prominent vessel is noted coursing through the posterior temporal lobe toward the lesion, which likely represents a feeding or draining vessel.

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC Pediatric supratentorial intraventricular tumors

signal intensity on T1- and T2-weighted images with het- alone appears to be a viable option as an initial treatment erogeneous enhancement. These lesions are frequently when postoperative imaging clearly confirms the absence calcified. of residual tumor.5,48,88,100 According to Palma, et al.,88 sur- The prognostic implications of histological grading of veillance imaging should be conducted every 4 to 6 ependymomas remain controversial, as little consensus months, with the duration of monitoring based on the has been reached on the value of specific histological fea- child’s age at the time of surgery and continued until the tures. Although highly cellular lesions with evidence of child exceeds the period of risk of recurrence according to cellular atypia, abundant mitotic activity, and vascular Collins' law (patient age at diagnosis + 9 months).13 A sec- proliferation suggest a higher propensity to recur, the pres- ond-look operation with the goal of total resection should ence of cellular atypia in isolation or the presence of be considered in cases in which local recurrence is found. necrosis does not appear to confer increased risk for recur- In children older than 3 years of age, radiotherapy is used rence. These lesions may recur even after an apparent in cases of inoperable or partially resected tumor, malig- macroscopically complete removal at the time of surgery. nant ependymomas, or following a second tumor resec- Because of the risk of recurrence, adjuvant therapies tion for recurrence.50,88 Spinal and craniospinal radiother- have been performed in children regardless of the extent apy is undertaken in children older than 3 years of age in of resection. Local recurrence represents the major pattern whom there is documented disseminated disease. For chil- of tumor recurrence.50,55 Management strategies have tra- dren younger than 3 years of age in whom residual tumor ditionally involved postoperative radiotherapy, although has been documented after initial resection, chemotherapy there has been a growing trend for the inclusion of che- can be administered and radiotherapy deferred until the motherapies. Whereas the beneficial effect of radiothera- child is older.50 py on survival has been documented,86,126,130 the specific Meningiomas. Intracranial meningiomas are relatively role of radiotherapy in the treatment of intracranial epen- rare in children, accounting for less than 2% of all intra- dymomas in children is debated.40,50,78 Conventional radio- cranial neoplasms in this population.34,54,71 Meningiomas therapy, when combined with resection of intracranial that occur in children differ in many respects from those ependymomas, has resulted in improved 5-year survival in adults. In the pediatric population, intracranial menin- and 5-year progression-free survival rates.41,84,93,108 Be- giomas are more likely to be intraventricular and cys- cause of the long-term sequelae associated with conven- tic,8,34,125 malignant,22 and demonstrate multiplicity.24 Neu- tional radiotherapy, however, most pediatric centers have rofibromatosis Type 2 should be considered in the young significantly limited the extent of its use in the treatment patient with an intracranial meningioma, especially in the of the young child. The authors of a recent preliminary setting of multiple lesions. The female predominance study investigating the role of postoperative radiosurgery noted in adults is not observed in children.71 When menin- in patients with intracranial ependymomas did not find a giomas occur in the older child or adolescent, they also significant benefit with regard to prevention of long-term tend to be supratentorial in origin and intraventricular in recurrence.95 Similarly, the utility of chemotherapy in the location, but clinically they demonstrate an affinity for management of intracranial ependymomas remains equiv- behaving like those found in adults. The atrium of the lat- ocal, as there is little evidence demonstrating improve- 11,55,120 eral ventricle is the most common intraventricular loca- ment in survival rates. tion.22,51 In fact, meningioma is the most common in the Despite improvements in progression-free and overall trigonal demonstrated mass after the first decade of life. survival rates reported in recent series, the overall prog- nosis remains relatively poor for children with intracranial Patients with intracranial meningiomas typically pre- ependymomas. Mounting evidence, however, suggests sent with signs of hydrocephalus. Because of their affinity that supratentorial ependymomas may represent a sub- for the trigone, these lesions can cause atypical psycho- group of intracranial ependymomas with different prog- motor or temporal lobe seizures. Intraventricular menin- nostic implications than their infratentorial counterparts. giomas are well-circumscribed, lobulated masses that are Complete resection of intracranial ependymomas without typically hyperdense on CT scans and isointense with brain on T -weighted MR images. Nearly all enhance further therapies has been associated with improved long- 1 term tumor-free survival.5,55,56,60,69,78,83,88,94,100,120 Although intensely after contrast administration. Calcifications are some authors have noted that supratentorial ependymo- often noted. Complete resection is most often curative. mas have a poorer prognosis compared with their poste- The treatment of subtotally resected meningiomas in chil- 60 dren remains controversial, especially in the setting of rior fossa counterpart, other authors have noted that total 8 resection is more often achieved in patients with supra- NF. Incomplete excision, the presence of a focal neuro- 5,33,87, logical deficit at the time of diagnosis, and malignant his- tentorial as opposed to infratentorial ependymomas, 71 88,100 especially in cases of lateral ventricular tumors or tology have been associated with poor outcome. As with extraventricular tumors located far from eloquent cor- other neoplasms located in the lateral ventricle, significant tex.33,87 It has also been noted that complete resection blood loss can occur when these tumors are manipulated without adjuvant therapy represents a viable option in the during the surgical exposure. Preoperative angiography treatment of supratentorial ependymomas.5,56 In a cooper- and embolization should be considered in selected cases. ative study published by the Children’s Cancer Group, total resection was achieved in 64% of cases of supraten- Body of the Lateral Ventricle torial ependymomas as opposed to 38% of infratentorial In the young child, intraventricular masses that involve ependymomas. Radical resection and the extent of resid- the body of the lateral ventricle include astrocytoma, ual tumor demonstrated on postoperative imaging were PNET, and teratoma. Most of these lesions arise from the only significant prognostic factors.100 Radical surgery ependymal and subependymal tissue surrounding the ven-

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC D. Y. Suh and T. Mapstone tricle and extend into the low-resistance ventricular cavi- JPAs are rarely found in the trigone.114 Radiographically, ty. In older children anaplastic astrocytoma with intraven- JPAs are usually well-circumscribed solid lesions with a tricular extension is the most common ventricular tumor cystic component that contains a mural nodule. These involving the frontal horn or ventricular body. lesions demonstrate low signal intensity on T1-weighted Astrocytoma. Astrocytomas account for approximately MR images and enhancement with contrast, which can 35% of all brain tumors in children. The most malignant help to distinguish them from diffuse astrocytomas or forms occur supratentorially, as opposed to the benign well-differentiated fibrillary astrocytomas. In adults, later- varieties, which are more commonly seen infratentorially. al ventricular astrocytomas are more likely to be higher- Lateral ventricular astrocytomas typically arise from grade tumors with heterogeneous signal, associated peri- extraventricular structures that are located adjacent to the tumoral edema, and enhancement after administration of ventricle. The thalamus is a common site of origin for contrast material. astrocytic tumors that expand into the ventricle. As such, Treatment is determined by histological grade, lesion there can be relatively little intraparenchymal displace- location, imaging characteristics, patient age, and clinical ment, even with large tumors. Children with malignant presentation. High-grade lesions are treated with radio- astrocytomas tend to fare better in terms of outcome than and/or chemotherapy. In terms of low-grade gliomas, adult with malignant astrocytomas. This is likely a reflec- most authors agree that completely microscopically resec- tion of the larger portion of anaplastic astrocytomas and ted JPAs do not require further therapy. Recurrence-free the smaller number of glioblastomas multiforme that survival without adjuvant therapies has been reported to occur in children. The most common histological types approach nearly 100%.37,127 Therefore, total resection is re- include fibrillary astrocytoma, JPA, and SGCA. commended for JPAs when technically feasible. Regard- Fibrillary astrocytomas may be diffuse and infiltrative, less of location, however, the natural history of JPA is one or they may be more circumscribed and noninfiltrative. of slow, indolent growth, and many physicians will man- They may extend within the corpus callosum to involve age these tumors expectantly, especially in cases of tumors both hemispheres. The more infiltrative lesions are ob- involving the optic pathways95 or in children with NF1. served to be hypodense on CT scans and do not enhance. The treatment of subtotally resected JPAs or low-grade These tumors are rarely associated with peritumoral gliomas remains controversial. The 10-year survival rates edema. Calcifications are present in 20% of cases. On MR of nearly 75% following subtotal resection or biopsy sam- imaging, more infiltrative lesions demonstrate mildly de- pling37 have prompted some authors to recommend limit- creased signal intensity on T1- and hyperintensity on T2- ed surgery and adjuvant therapies in cases of lesions in weighted images. Focal lesions have more well-defined which total resection is associated with a high morbidity 121 hypointensity on T1- and hyperintensity on T2-weighted rate. Others defer the use of adjuvant therapies follow- images. These masses typically do not enhance, although ing subtotal resection until there is evidence of disease mild enhancement can be seen (Fig. 3). progression.19,89,127 Mamelak, et al.,72 have recommended Juvenile pilocytic astrocytomas most often occur in- that children older than 5 years of age in whom low-grade fratentorially and have a distinct predilection for the cere- gliomas were subtotally resected undergo focal radiother- bellum. These tumors are found supratentorially in 11% of apy and that both chemo- and radiotherapy be given if children with intracranial neoplasms and demonstrate a neuraxis dissemination is discovered. These authors fur- preference for the opticohypothalamic region. Less fre- ther noted a risk for multicentric disease in some patients quently, JPAs involve the anterior body of the lateral with JPAs, especially with tumors involving the hypothal- ventricle and rostral third ventricle.37,61,63 Intraventricular amic region. The role of radiotherapy in the treatment of

Fig. 3. Magnetic resonance imaging studies demonstrating diffusely infiltrating astrocytoma with an exophytic com- ponent at the foramen of Monro. Prior to this study, the patient had undergone placement of a right frontal ventricular

catheter for treatment of hydrocephalus. Axial (A) and sagittal (B) T1-weighted images revealing a diffusely infiltrating lesion involving the brainstem and thalamus. Axial (C) T2-weighted images demonstrating extensive hyperintensity in the entire pons, ventral and mid-portion of the midbrain bilaterally, and bilateral involvement of the thalami and striate

nuclei, optic chiasm, intracranial optic nerves, and hypothalamus. Axial (D) and coronal (E) T1-weighted gadolinum- enhanced images revealing relatively little abnormal enhancement. There is, however, a nodular soft-tissue enhancing lesion at the foramen of Monro.

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC Pediatric supratentorial intraventricular tumors progressive low-grade gliomas is not clear in terms of the suprasellar region or intraventricularly in the body of long-term survival. A growing body of evidence suggests the lateral ventricles. Histologically, they are divided into that chemotherapy may delay disease progression of low- mature or immature types based on the degree of differen- grade gliomas, thereby obviating or delaying the need for tiation of the components. Imaging findings are variable, radiotherapy or radical resection.98 Chemotherapy should with heterogeneous signal characteristics observed on MR be strongly considered in young children with evidence of images. Because of their circumscribed nature, mature ter- a progressive low-grade glioma that is not amenable to atomas and, at times, malignant teratomas are amenable to complete resection. complete resection and cure. Radiotherapy is not effective Although the overall survival for patients with JPAs is for unresected tumors.128 quite favorable, even when the tumors are incompletely resected, clearly not all low-grade gliomas behave in a Frontal Horn and Foramen of Monro clinically benign fashion. Up to one third of JPAs behave Primary septal neoplasms are uncommon. Thickening aggressively.117 These tumors can disseminate to the neu- of the septum pellucidum greater than 3 mm is suggestive raxis on rare occasions or undergo malignant transforma- of an infiltrating neoplasm, most commonly an astrocy- tion at the time of progression.14,19,72 Some low-grade toma. Dysplastic thickening of the septum can be seen in gliomas appear to progress erratically and do not adhere to patients with NF1. Dysembryoplastic epithelial tumorÐ Collins' law, making treatment planning difficult.98 like lesions of the septum pellucidum have been described Primitive Neuroectodermal Tumor. The term PNET in children and young adults.6 These lesions are often represents a group of small cell embryonal tumors of the misdiagnosed as gliomas, but they are clinically, radio- CNS that exhibit divergent differentiation. Although his- graphically, and histologically benign tumors. In the tologically similar, these tumors are not equivalent and young child, the most common intraventricular tumors their histogenesis remains undetermined. Supratentorial located within the frontal horn at or near the foramen of PNETs are highly malignant in infants and young chil- Monro include SGCA, choroid plexus neoplasms, and dren, and they account for approximately 2 to 3% of all central neurocytomas. childhood brain tumors.39 Despite the rarity of these le- Subependymal Giant Cell Astrocytoma. These lesions sions, they represent the most common congenital brain are astrocytic-like variants found almost exclusively in tumor. At least 80% occur in the first decade of life, usu- patients with tuberous sclerosis. Subependymal giant cell ally before the age of 5 years, with many presenting before astrocytomas are discovered in 10 to 15% of patients with 1 year of age. Most PNETs are paraventricular masses, lo- tuberous sclerosis.81,109 Isolated or spontaneous formes cated in the deep white matter of the frontal or parietal frustes cases of SGCA have also been described. These lobes. The lesions that are intraventricular often involve tumors are low-grade, indolent, and calcified nodular sub- the body of the lateral ventricle and can reach significant ependymal lesions that usually arise in the foramen of size at the time of presentation. These tumors are large, Monro, with an associated soft-tissue mass located within bulky hemispheric masses that appear well circumscribed the frontal horn of the lateral ventricle. Although they are on imaging studies. Children typically present with signs mainly found in the regions of the foramen of Monro and of increased ICP, and CSF dissemination can occur.2 frontal horn, subependymal hamartomatous lesions can Radical excision is the preferred treatment along with occur anywhere along the ventricular system. Subepen- craniospinal radio- and chemotherapy as adjuvant thera- dymal hamartomatous nodules along the caudothalamic pies. The prognosis is generally poor but appears variable. groove or along the walls of the lateral ventricles are Nonpineal supratentorial PNETs respond differently to demonstrated in up to 90% of patients with tuberous scle- treatment than pineal supratentorial PNETs, especially in rosis. Only 2 to 14% of children with subependymal nod- infants. Encouraging results from the Children’s Cancer ules will develop tumors.109 Symptomatic lesions are typ- Group infant study indicate that a significant percentage ically restricted to the region of the foramen of Monro, of patients may be successfully treated with surgery and overlying the head of the caudate nucleus, and are associ- chemotherapy alone.2 Multimodal therapies such as resec- ated with increased ICP from hydrocephalus secondary to tion followed by craniospinal irradiation with a boost to foraminal obstruction. Symptomatic SGCAs tend to pre- the tumor site and adjuvant chemotherapy are recom- sent before the patient is 20 years of age. Histologically, mended in older children.58 these tumors are variable but tend to be characterized by Teratoma. Intracranial germ cell tumors typically arise large, bizarre-looking astrocytes. They grow progressive- in the midline, usually in the pineal or suprasellar region, ly and, on rare occasions, demonstrate malignant transfor- although some may originate more laterally in the thala- mation to glioblastoma. Frequently the diagnosis is guid- mus or basal ganglia and extend into the ventricle. These ed by the clinical and radiographic features. These tumors lesions are composed of elements from all three germinal demonstrate mixed density or isodensity on CT scans, layers. Although teratomas are relatively rare intracranial with variable areas of calcifications. They demonstrate neoplasms, their incidence increases in patients younger intense enhancement after contrast administration. On than 15 years of age. These lesions are the most common- MR imaging, the calcified subependymal tubers are hy- ly diagnosed hemispheric tumor in the neonate or infant pointense on T1- and T2-weighted images. The soft tissue and the most common intracranial neoplasm in stillborn component has heterogeneous signal intensity on T1- and 57 babies and neonates. Teratomas can arise at any site T2-weighted images with intense enhancement after con- within the craniospinal axis. Fifty percent of teratomatous trast administration (Fig. 4). lesions present in the posterior third ventricle, accounting Treatment is usually limited to resection and there is for 15% of pineal regions masses, the remainder occur in excellent long-term survival,25,102 although mortality rates

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Fig. 4. Imaging studies of SGCA involving both frontal lobes obtained in a 10-month-old girl with tuberous sclero- sis. Axial CT scans without (A) and with (B) contrast demonstrating an intraventricular mass with associated hydro-

cephalus. The mass is calcified along the right margin. Axial (C) T1-weighted MR image revealing that the mass involves both lateral ventricles, slightly more eccentric to the right. The mass is heterogeneous with low signal intensity noted in areas of known calcification along the right side of the lesion and within small cystic or necrotic areas along the left side of the lesion. The mass abuts and distorts the foramen of Monro greater on the right than left, and is intimately associat- ed with the septum pellucidum and the caudate nucleus, anterior thalamus, and caudothalamic groove on the right side. The chiasm does not appear to be involved, and the optic nerves and tracts are of normal size. Axial (D) and coronal (E)

T1-weighted gadolinum-enhanced MR images revealing extensive enhancement. No CSF seeding or remote intraven- tricular dissemination is appreciated. as high as 10% have been reported in those children who through the craniospinal axis, although this rarely oc- present acutely and require emergency surgery.82 Nabbout, curs.31 Atypical neurocytomas with malignant or aggres- et al.,81 have determined a number of radiographic charac- sive features have also been reported.4 Although radio- teristics that may help to differentiate presymptomatic therapy has been performed in patients with subtotally SGCAs with the potential for growth from subependymal resected tumors, the benefit to overall survival has not nodules without growth potential in patients with tuberous been established for those with typical central neurocy- sclerosis. According to these authors, subependymal nod- toma.62 Postoperative radiotherapy may be of benefit in ules that were localized near the foramen of Monro and selected patients inwhom there are residual tumors that measured greater than 5 mm, were incompletely calcified demonstrate either atypical or malignant characteristics.4 or noncalcified, or enhanced with gadolinum carried the In general, the overall prognosis is excellent. highest risk for tumor growth. These findings were noted as early as 1 year of age, prompting these authors to rec- ommend sequential MR imaging at the time of diagnosis TUMORS OF THE THIRD VENTRICLE and/or by 2 years of age. If suspicious nodules are identi- Primary third ventricular neoplasms are relatively rare fied, MR imaging should be performed annually until the regardless of patient age. The vast majority of neoplasms patient reaches the age of 10 years, especially in families that involve the third ventricle are astrocytomas originat- with a history of tuberous sclerosis. ing in the wall or the floor of the ventricle and affecting Central Neurocytoma. These discrete intraventricular the ventricle by direct extension. Most are low-grade tumors arise at the inferior septum pellucidum near the lesions and cause symptoms associated with increased foramen of Monro where they obstruct the flow of CSF hydrocephalus-induced ICP. Endocrinological deficits and and cause symptoms of increased ICP. Most of these visual disturbances are typically uncommon with tumors lesions occur in young to middle-aged adults. Noncentral arising from within the third ventricle. When visual dis- neurocytomas have also been described, either arising in turbance is demonstrated, it is usually secondary to extra- the spinal cord or within the cerebral parenchyma.107,123 ventricular involvement or optic pathway compression Histologically, they were often thought to be oligoden- due to ventricular distortion. Mass effect on the hypothal- drogliomas, and only recently have they been better doc- amus or hypothalamic involvement can result in the dien- umented and characterized. The pathological diagnosis is cephalic syndrome, which is classically seen in infants greatly aided by immunohistochemistry, which shows and is manifest by emaciation combined with hyperalert- neuronal markers. These tumors are strongly positive for ness. Lesions located in the posterior segment of the third neuron-specific enolase and synaptophysin. The radiolog- ventricle can result in mass effect on the pretectal region ical characteristics of these tumors are relatively nonspe- and/or obstruction of CSF flow. cific. They appear to be well circumscribed and have het- A variety of tumors can occur in the third ventricle in erogeneous density and signal on CT or MR imaging. children, with certain masses more commonly found in Enhancement is also variable. Many central neurocytomas the anterior portion compared with the posterior portion of are calcified. Total resection is potentially curative. Re- the third ventricle. The more common anterior third ven- currence does occur in subtotally resected lesions, al- tricular neoplasms are hypothalamic astrocytoma and su- though the rate of regrowth is typically slow. Moreover, prasellar craniopharyngioma. Choroid plexus papilloma, despite their benign histology, they may disseminate germinoma, teratoma, and ependymoma occasionally are

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC Pediatric supratentorial intraventricular tumors seen in children. Ten percent of CPPs involve the third presentation and natural history dependent on location. ventricle and occur primarily in children younger than 5 Although these lesions appear macroscopically well de- years of age. Fifteen percent of all supratentorial ependy- fined, they usually infiltrate the optic pathways and hypo- momas present within the third ventricle. Epidermoid and thalamus. Some of these tumors, however, progress more dermoid tumors occur uncommonly in the anterior third rapidly or disseminate to the neuraxis. This is especially ventricle. true for low-grade gliomas involving the hypothalamus A number of nonneoplastic entities that occur in the an- and chiasm.59,72 terior body of the third ventricle deserve mention. Colloid Multicentric pilocytic tumors of the optic nerve are par- cysts represent the most common anterior third ventricular ticularly common in patients with NF1. As many as 70% mass demonstrated in adults. These lesions can occur in of optic pathway tumors are pilocytic astrocytomas asso- adolescents and young adults but seldom occur in young ciated with NF1.67 These tumors tend to be very low grade children. Both microsurgical and endoscopic procedures and have a more benign course with favorable progno- have been performed to resect these lesions, and the sis.103 In a longitudinal study the authors documented that results have been good. Histiocytosis represents a com- in children with NF1 and isolated optic nerve gliomas dis- mon anterior third ventricular mass lesion found in chil- ease progression tended not to occur.66 In fact, a case of dren; these lesions tend to arise in the suprasellar region spontaneous regression of an optic glioma in a child with from the floor of the third ventricle and may invade the NF1 has been reported.15 hypothalamus. Children with these lesions can present In children in whom the bulk of the tumor occupies the with evidence of pituitaryÐhypothalamic dysfunction and ventricle, the most common clinical presentation involves bony skeletal lesions. There appears to be a slight male symptoms of hydrocephalus, but visual disturbance is sel- predominance. The goal of surgical intervention is pri- dom a predominant complaint. Endocrinological and/or marily to obtain a biopsy sample to determine a diagnosis, hypothalamic dysfunction tend to occur late in the disease as these lesions are extremely radiosensitive. Cysticer- process. In contrast to their cerebellar counterparts, which cosis is the most common parasitic infection involving the tend to be cystic masses with a mural nodule, opticochias- CNS; it is caused by the intestinal tapeworm Taenia soli- maticÐhypothalamic JPAs are usually solid lesions and um and is endemic in some areas of Mexico and certain rarely have associated cysts. Radiographically, they ap- Third World countries. In the United States, cysticercosis pear iso- to hypodense to brain on CT scans, iso- to hypo- is a rare entity more commonly found in the Western and intense on T -weighted MR images, and hyperintense on Southwestern regions. The favored location of cystic 1 T2-weighted MR images. These tumors show mild to lesions is either meningeal or within brain parenchyma. moderate enhancement with contrast. Treatment is re- Approximately 12 to 18% are located intraventricularly, served for symptomatic patients, and observation is often possibly gaining access via the choroid plexus. Ventricular recommended especially for children with NF1. involvement is associated with higher patient morbidity and mortality. Cysts may travel via the ventricular system Craniopharyngioma. Craniopharyngiomas represent and can cause obstructive hydrocephalus, although the the most common nonglial neoplasms in children, ac- classic clinical presentation in children involves repeated counting for 1 to 2% of all intracranial neoplasms and bouts of meningitis rather than hydrocephalus. Treatment nearly 50% of all suprasellar masses in children. The peak of intraventricular cysticercal cysts typically involves incidence of craniopharyngiomas occurs when the patient three possible options: antihelmintic therapy, CSF diver- is between 5 and 10 years of age. There is a second, small- er peak incidence noted between the fifth and sixth sion, and/or resection of the cysts. Surgery may be neces- 53 sary to establish a diagnosis or to treat intraventricular decades. Lesions that involve the third ventricle primar- lesions that appear to be less responsive to medical ther- ily arise extraventricularly along the infundibular stalk or apy. Cerebrospinal fluid diversion for symptomatic hy- in the floor of the anterior portion of the third ventricle drocephalus is frequently necessary. Endoscopic man- with ventricular extension. Purely intraventricular cranio- pharyngiomas are rare, however, with fewer than 30 pedi- agement of intraventricular cysticercal cysts, used in 70 combination with third ventriculostomy or septum pellu- atric cases reported in a recent review. The clinical pre- cidotomy in selected cases, has also been described.10 sentation typically involves a combination of symptoms of raised ICP or manifestations of visual, hypothalamic, or Anterior Third Ventricular Masses endocrinological dysfunction. The majority of third ventricular CPs appears to be of Juvenile Pilocytic Astrocytoma. Juvenile pilocytic as- the papillary type and accounts for approximately 10% of trocytomas represent 5 to 10% of all cerebral gliomas and all craniopharyngiomas. The classic adamantinomatous account for approximately one third of glial neoplasms lesion is typically found in the suprasellar region. The two occuring in children. The majority of JPAs are supratento- variants of craniopharyngioma are not only distinct in rial, arising from the floor of the third ventricle in the chi- terms of their morphological features, but also in their asmalÐhypothalamic region and extending into the third age-related incidence, location, radiographic appearance, ventricle. Approximately one third of JPAs are infratento- and prognosis. Papillary craniopharyngiomas are solid, rial, located in the cerebellar vermis or hemispheres. Op- noncalcified masses that are seldom cystic and are more ticochiasmaticÐhypothalamic JPAs are one of the most frequently encountered in adults. A dissection plane that common supratentorial neoplasms in childhood, with separates papillary tumor from the surrounding brain tis- nearly 75% of optic pathway JPAs presenting in patients sue allows for total excision.1,21 In a review of the Mayo younger than 12 years of age.101 Low-grade gliomas are Clinic experience, Duff, et al.,27 found no difference in usually indolent, slow-growing neoplasms with symptom outcome or recurrence rates between papillary and adam-

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC D. Y. Suh and T. Mapstone antinomatous tumors. Thus, even though craniopharyn- fundibular stalk. Occasionally, there is a synchronous giomas are well circumscribed, they are not encapsulated. pineal region tumor.118 In rare cases, these tumors arise in Moreover, they tend to become insinuated among and the thalamus or basal ganglia. There is a strong male pre- adherent to vital neurovascular structures, making radical dominance, with most patients presenting between the resection extremely difficult. This adhesiveness to sur- ages of 10 and 30 years for germinomas involving the rounding neural and vascular structures is a risk factor for pineal region.64 Both pineal and suprasellar region germi- poor outcome and/or tumor recurrence.23,27 Adamantino- nomas occur during the first three decades of life and matous craniopharyngiomas are more commonly seen in more often at the onset of puberty. Symptoms depend on children and tend to be cystic, calcified, suprasellar le- the site of growth and the degree of invasion of adjacent sions that are more likely to recur. On MR imaging these structures. Patients with anterior third ventricular germi- lesions have the most heterogeneous signal characteristics noma generally present with visual loss, decreased libido, of all sellar region masses. The signal is highly variable and diabetes insipidus. Diffuse ependymal and subarach- and dependent on the cyst contents. Craniopharyngiomas noid seeding is common. Computerized tomography scan- enhance strongly but heterogeneously after contrast ad- ning typically reveals a hyperdense lesion. On MR imag- ministration (Fig. 5). ing, germinomas tend to be isointense on T1- and T2- Treatment of these histologically benign but locally weighted images. They demonstrate homogeneous en- aggressive lesions remains controversial. Radical resec- hancement after contrast administration. tion has been the mainstay of treatment. Early enthusiasm Because management of CNS GCTs is complicated by for radical surgical approaches, however, has been damp- the diversity of histological subtypes, accurate diagnosis ened by the recognition that aggressive resection (particu- is paramount to determining the optimal treatment strat- larly for retrochiasmatic and giant craniopharyngiomas) egy. One key factor is to differentiate pure germinomas was frequently associated with significant morbidity and a from those GCTs that contain an admixture of nongermi- relatively high rate of recurrence.23,35,53,96,122,131 Therefore, nomatous elements (choriocarcinoma, endodermal sinus efforts have been focused on combining less aggressive tumor, or embryonal carcinoma). Collectively, the mixed resection with adjuvant therapies as a primary treatment, forms are less responsive to adjuvant therapies than pure and the reported results are comparable with those of rad- germinomas.73 Pure germinomas are typically nonsecret- ical resection.23,36,43,97,106,129 Others have advocated a staged ing tumors, whereas nongerminomatous GCTs are secret- surgical approach and the early incorporation of conserv- ing tumors, based on elevations of either -fetoprotein or ative measures such as stereotactically guided cyst aspir- HCG in the serum or the CSF. There is also some evi- ation/instillations as a strategy to defer the undertaking dence to suggest that typical germinomas may occasional- of external fractionated radiotherapy until a child is old ly contain foci of syncytiotrophoblastic cells, which are enough.23,47 The ultimate role of stereotactic radiosurgery strongly reactive for HCG and human placental lacto- for these lesions is currently undefined but appears gen. Placental alkaline phosphatase also appears to be a promising.18,68,95 marker for intracranial germinomas. Although the clinical Germinoma. Pure germinomas are the most common significance of this variant of HCGÐsecreting germi- primary CNS GCT, accounting for 65% of all CNS noma is not clearly established, as these tumors do not GCTs.128 Although they occur more often in the pineal appear to mimic the aggressive malignant behavior of region, however, suprasellar germinomas can also present choriocarcinomas, they may be associated with a higher in the anterior third ventricle via extension from the in- recurrence rate than germinomas without syncytiotro-

Fig. 5. Magnetic resonance imaging studies of suprasellar craniopharyngioma obtained in a patient after placement of a right ventriculoperitoneal shunt for treatment of hydrocephalus. There is a large suprasellar mass that extends into the sella, third ventricle, and into the right middle fossa to the cerebellopontine angle. The lesion displaces the chiasm ante-

riorly and the upper pons and midbrain dorsally, with compression of the brainstem. Precontrast T1- and T2-weighted MR images (not shown) demonstrated heterogeneous signal intensity on all sequences with multiple areas of cystic change.

There was extensive calcification noted. Following the adminstration of gadolium, axial (A and B), and coronal (C) T1- weighted MR images demonstrated heterogeneous enhancment throughout the lesion and rim enhancement in several of the larger cystic regions.

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Unauthenticated | Downloaded 09/25/21 06:16 AM UTC Pediatric supratentorial intraventricular tumors phoblastic components.132 Other authors have not found 20% of all intraventricular masses and represent the most any difference in recurrence rates for HCGÐsecreting common mass lesion found in the anterior portion of the germinomas.105,112 Fortunately, a significant proportion of third ventricle. The histogenesis of colloid cysts remains CNS GCTs can be diagnosed by analysis of tumor mark- unclear. They are rare in children, with only 1 to 2% oc- ers expressed in the serum or CSF or based on tissue spec- curring in patients younger than 10 years of age. Colloid imens obtained by biopsy sampling or resection. Biopsy cysts rarely become symptomatic before the patient reach- sampling of these malignant GCTs carries the inherent es 20 years of age and are usually found in adults in the risk of histological sampling error, particularly in tumors second to fourth decades of life. Clinical behavior is the with mixed elements. Serial analysis of these markers is same in children as adults. Symptoms of intermittent also essential to determine and monitor treatment re- hydrocephalus are common and sudden death secondary sponse. Tumor marker levels in the serum and CSF must to acute obstruction has been reported, although in the be collected simultaneously, because it is common for majority of cases of sudden death there appeared to be a normal levels to be observed in the serum while CSF lev- history of symptoms indicating increasing ICP that pre- els are elevated. This finding is especially prevalent in ceded the event by weeks to months. Occasionally, acute germinomas.128 In addition, CSF specimens should be hemorrhage within the cyst may be the presenting clinical obtained from ventricular fluid intraoperatively or within symptom. Imaging characteristics vary depending on the 1 to 2 days postoperatively. contents of the cyst. Because pure germinomas are extremely radiosensi- tive, until recently radiotherapy has remained the corner- Posterior Third Ventricular Masses stone of treatment.104,128 A variety of dosing schemes and A variety of tumors may arise from the region of the volumes have been described: whole-ventricle irradia- posterior region of the third ventricle, reflecting the varied tion,73,113 high-dose whole-brain irradiation, craniospinal tissue types that originate in this region. The majority of irradiation,45 and/or low-dose irradiation to the craniospi- neoplasms are glial in nature (two thirds of which are usu- nal axis.46 Others advocate low-dose (20Ð24 Gy) prophy- ally high grade) and include astrocytomas and, to a lesser lactic irradiation to the craniospinal axis in patients with extent, ependymomas. A number of tumors arise from the positive CSF cytological findings or evidence of dissemi- pineal region and have been reviewed in preceding sec- nation demonstrated on the initial MR images.110,111 In the tions. These include the pineal region germinomas and past, it was commonplace to assess the radiosensitivity of teratomas. Pineal parenchymal tumors such as pineoblas- a lesion by delivering a single fractionated dose to the tomas, pineocytomas, and other GCTs (embryonal cell tumor site, even without initially determining a diagnosis carcinomas and choriocarcinomas) are rare tumors that based on examination of tissue specimen. If a radiograph- arise in the posterior third ventricle. Regardless of the ic response was demonstrated, the tumor was considered tumor type, lesions in the posterior third ventricle cause a to have germinal origin, and high-dose focal radiotherapy similar constellation of symptoms related to obstructive was initiated.99 Because of the associated long-term se- hydrocephalus or involvement of the pretectal plate and quelae and morbidity of craniospinal radiotherapy in resulting in Parinaud syndrome. young children, however, recent strategies have been developed to avoid or reduce the role of radiotherapy in the treatment of germinomas. It has become more preva- SUMMARY lent to initiate chemotherapy as the primary treatment for Supratentorial intraventricular lesions in children are patients with CNS GCTs. Pure germinomas demonstrate heterogeneous with regard to tumor type and treatment. an 80% complete radiographic response with chemother- Establishing a tissue diagnosis is usually required for ac- apeutic regimens, regardless of the extent of tumor resec- curate treatment planning, and resection without adjuvant tion.128 A standard approach for patients in whom CNS therapy can be curative in cases of selected tumor types. GCTs have been diagnosed by the presence of positive The tumor location, age of the patient, and imaging char- tumor markers or by biopsy sample may entail initial acteristics can help to narrow the focus of the differential chemotherapy followed by radiographic surveillance for diagnosis. Careful preoperative neuroimaging is extreme- residual tumor after completion of two to four cycles. A ly useful in treatment planning because a small subset of second-look surgical intervention to resect the lesion or to these lesions is treated expectantly. obtain biopsy sample is reserved for patients in whom an incomplete radiographic response is demonstrated, de- References spite the normalization of tumor markers.7 Those who 1. Adamson TE, Wiestler OD, Kleihues P, et al: Correlation of have not responded have been found to harbor either fi- clinical and pathological features in surgically treated cranio- brotic/necrotic tissue or a teratomous lesion at second- pharyngiomas. J Neurosurg 73:12Ð17, 1990 16 look surgery. If the teratoma is mature, excision is cura- 2. Albright AL, Wisoff JH, Zeltzer P, et al: Prognostic factors in tive and no further therapy is indicated. If an immature children with supratentorial (nonpineal) primitive neuroecto- teratoma is confirmed, local-field irradiation is initiated dermal tumors. A neurosurgical perspective from the Children's after resection. Some investigators have also suggested Cancer Group. Pediatr Neurosurg 22:1Ð7, 1995 that radical resection of nongerminomatous GCTs may 3. Al-Yamany M, Del Maestro RF: Prevention of subdural fluid offer some survival benefit.7,73,128 collections following transcortical intraventricular and/or par- aventricular procedures by using fibrin adhesive. J Neurosurg Colloid Cyst. These histologically benign lesions are 92:406Ð412, 2000 typically found in the roof of the third ventricle at the level 4. Ashkan K, Casey AT, D'Arrigo C, et al: Benign central neuro- of the foramen of Monro. Colloid cysts account for 15 to cytoma. Cancer 89:1111Ð1120, 2000

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5. Awaad YM, Allen JC, Miller DC, et al: Deferring adjuvant ther- 28. Duffner PK, Cohen ME, Horowitz M, et al: The treatment of apy for totally resected intracranial ependymoma. Pediatr choroid plexus carcinoma in infancy with chemotherapy. Ann Neurol 14:216Ð219, 1996 Neurol 26:460, 1989 (Abstract) 6. Baisden BL, Brat DJ, Melhem ER, et al: Dysembryoplastic neu- 29. Duffner PK, Kun LE, Burger PC, et al: Postoperative che- roepithelial tumor-like neoplasm of the septum pellucidum: a motherapy and delayed radiation in infants and very young lesion often misdiagnosed as glioma: report of 10 cases. Am J children with choroid plexus carcinomas. The Pediatric On- Surg Pathol 25:494Ð499, 2001 cology Group. Pediatr Neurosurg 22:189Ð196, 1995 7. Balmaceda C, Heller G, Rosenblum M, et al: Chemotherapy 30. Ellenbogen RG, Winston KR, Kupsky WJ: Tumors of the without irradiation—a novel approach for newly diagnosed choroid plexus in children. 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Gaffney CC, Sloane JP, Bradley NJ, et al: Primitive neuroecto- tion for CNS germ cell tumors. J Clin Oncol 17:933Ð940, 1999 dermal tumours of the cerebrum. J Neurooncol 3:23Ð33, 1985 17. Childhood Brain Tumor Consortium: A study of childhood 40. Goldwein JW, Corn BW, Finlay JL, et al: Is craniospinal irradi- brain tumors based on surgical biopsies from ten North Ameri- ation required to cure children with malignant (anaplastic) in- can institutions: sample description. J Neurooncol 6:9Ð23, tracranial ependymomas? Cancer 67:2766Ð2771, 1991 1988 41. Goldwein JW, Leahy JM, Packer RJ, et al: Intracranial epen- 18. Chung WY, Pan DH, Shiau CY, et al: Gamma knife radiosur- dymomas in children. Int J Radiat Oncol Biol Phys 19: gery for craniopharyngiomas. J Neurosurg 93 (Suppl 3): 47Ð56, 2000 1497Ð1502, 1990 19. Civitello LA, Packer RJ, Rorke LB, et al: Leptomeningeal dis- 42. Greenberg ML: Chemotherapy of choroid plexus carcinoma. semination of low-grade gliomas in childhood. 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98. Reddy AT, Packer RJ: Chemotherapy for low-grade gliomas. 117. Strong JA, Hatten HP Jr, Brown MT, et al: Pilocytic astrocy- Childs Nerv Syst 15:506Ð513, 1999 toma: correlation between the initial imaging features and clin- 99. Rich TA, Cassady JR, Strand RD, et al: Radiation therapy for ical aggressiveness. AJR 161:369Ð372, 1993 pineal and suprasellar germ cell tumors. Cancer 55:932Ð940, 118. Sugiyama K, Uozumi T, Kiya K, et al: Intracranial germ-cell 1985 tumor with synchronous lesions in the pineal and suprasellar 100. Robertson PL, Zeltzer PM, Boyett JM, et al: Survival and regions: report of six cases and review of the literature. Surg prognostic factors following radiation therapy and chemother- Neurol 38:114Ð120, 1992 apy for ependymomas in children: a report of the Children's 119. Sutton LN, Golden JA, Needle M, et al: Surgical removal of a Cancer Group. J Neurosurg 88:695Ð703, 1998 choroid plexus adenoma using the argon beam coagulator: 101. 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Ann NY Acad Sci 615:378Ð379, 1991 Radiat Oncol Biol Phys 17:1313Ð1321, 1989 110. Shibamoto Y, Abe M, Yamashita J, et al: Treatment results of 130. Whitaker SJ, Bessell EM, Ashley SE, et al: Postoperative radi- intracranial germinoma as a function of the irradiated volume. otherapy in the management of spinal cord ependymoma. J Int J Radiat Oncol Biol Phys 15:285Ð290, 1988 Neurosurg 74:720Ð728, 1991 111. Shibamoto Y, Oda Y, Yamashita J, et al: The role of cerebro- 131. Yas¸argil MG, Curcic M, Kis M, et al: Total removal of cran- spinal fluid cytology in radiotherapy planning for intracranial iopharyngiomas. Approaches and long-term results in 144 germinoma. Int J Radiat Oncol Biol Phys 29:1089Ð1094, patients. J Neurosurg 73:3Ð11, 1990 1994 132. Yoshida J, Sugita K, Kobayashi T, et al: Prognosis of intracra- 112. Shibamoto Y, Takahashi M, Sasai K: Prognosis of intracranial nial germ cell tumours: effectiveness of chemotherapy with germinoma with syncytiotrophoblastic giant cells treated by cisplatin and etoposide (CDDP and VP-16). Acta Neurochir radiation therapy. Int J Radiat Oncol Biol Phys 37:505Ð510, 120:111Ð117, 1993 1997 133. Zuccaro G, Sosa F, Cuccia V, et al: Lateral ventricle tumors in 113. Shirato H, Nishio M, Sawamura Y, et al: Analysis of long- children: a series of 54 cases. Childs Nerv Syst 15:774Ð785, term treatment of intracranial germinoma. Int J Radiat Oncol 1999 Biol Phys 37:511Ð515, 1997 114. Sim KB, Hong SK: Multicentric juvenile pilocytic astrocy- toma occurring primarily in the trigone of the lateral ventricle. Childs Nerv Syst 15:477Ð481, 1999 115. Souweidane MM, Johnson JH Jr, Lis E: Volumetric reduction Manuscript received May 2, 2001. of a choroid plexus carcinoma using preoperative chemother- Accepted in final form May 25, 2001. apy. J Neurooncol 43:167Ð171, 1999 Address reprint requests to: Timothy Mapstone, M.D., Depart- 116. St Clair SK, Humphreys RP, Pillay PK, et al: Current man- ment of Neurosurgery, Emory University School of Medicine, agement of choroid plexus carcinoma in children. Pediatr 1365-B Clifton Road, North East, Suite 6400, Atlanta, Georgia Neurosurg 17:225Ð233, 1991Ð92 30322, email: [email protected].

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